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US Pharm. 2012;37(6):HS-14-HS-16.
Polymyalgia rheumatica (PMR) is an
inflammatory condition of the muscles and joints and is characterized
by stiffness and pain in the neck, shoulders, hips, and buttocks.
Morning stiffness that lasts several hours is common. The onset of pain
can be sudden or gradual and affects both sides of the body.
Approximately 15% of patients with PMR develop giant cell arteritis
(GCA), and nearly 50% of patients with GCA will develop PMR over time.1
PMR is a complicated disease with many
complex symptoms. An accurate diagnosis must exclude many other
potential diseases. Corticosteroids (e.g., prednisone) are considered
the treatment of choice. Patients have an excellent prognosis, although
exacerbations may occur if steroids are tapered too rapidly, and
relapse is common.1
While there have been no major studies on the
relationship between inflammatory foods (e.g., wheat products) and PMR,
many patients have reported that by following a paleo or gluten-free
diet and exercising, they have been able to control their symptoms and
taper off the steroids in a period of up to 1 year. In general,
avoiding foods that cause inflammation and gastrointestinal problems
can sometimes alleviate fibromyalgia. Fibromyalgia affects about 2% of
the U.S. population, with women older than 50 years being more
susceptible to the disorder than men.2
Pathophysiology
The cause of PMR is unknown. PMR is
closely linked to GCA, although the two are believed to be separate
disease processes. Patients with PMR often have elevated levels of
interleukin-2 and interleukin-6. The pattern of T cell–derived
cytokines distinguishes these patient populations.
One hypothesis is that in a genetically
predisposed patient, an environmental factor, possibly a virus, causes
monocyte activation, which helps the production of the cytokines that
induce PMR and GCA. The prevalence of antibodies to adenovirus and
respiratory syncytial virus is reportedly higher in patients with PMR.
Increased occurrence in siblings suggests a genetic role in the
pathophysiology of the disease.3
Although PMR causes severe pain in the
proximal muscle groups, no evidence of disease is present on muscle
biopsy. Muscle strength and electromyographic findings are normal. Some
evidence suggests the presence of cell-mediated injury to the elastic
lamina in the blood vessels of the affected muscle groups.
The disease is more common among
northern Europeans, which may indicate a genetic predisposition. As
mentioned earlier, other risk factors for PMR are age of 50 years or
older and the presence of GCA. An autoimmune process may play a role in
PMR development.3
Epidemiology
In the U.S., the average annual incidence of PMR is 52.5
cases per 100,000 persons aged 50 years and older. The prevalence was
nearly 0.5% to 0.7%, but it is now up to 2%.
In Europe, the frequency decreases from
north to south, with a high incidence in Scandinavian countries and low
incidences in Mediterranean countries. In Italy, for example, the
incidence is 13 cases per 100,000 persons.
Whites are affected with PMR more than
other ethnic groups. PMR is twice as common in females, and the
incidence increases with advancing age.4
Signs and Symptoms
The signs and symptoms of PMR are
variable and nonspecific. The general symptoms are fatigue, low-grade
temperature, and limb swelling with pitting edema. The main symptoms
are musculoskeletal; however, there is normal muscle strength and no
muscle atrophy.
The majority of patients have pain in
the shoulder and hip without significant clinical swelling that reduces
mobility. Tenderness, palpations, and decreased active range of motion
in the musculature of the proximal hip, leg, shoulder, and arm cause
patients to do less exercise and therefore gain weight.
Over time, disuse of muscle causes
atrophy with proximal muscle weakness. In addition, contractures of the
shoulder capsule may lead to limitations of passive and active movement.5
Laboratory Diagnosis
Laboratory tests and studies in PMR include the following:
• The erythrocyte sedimentation rate
(ESR) is the most sensitive diagnostic study for PMR, although it is
not specific. The ESR is frequently elevated and greater than 40 mm/h,
but it can exceed 100 mm/h. In 20% of patients, the ESR is mildly
elevated or, occasionally, normal, which may occur in patients with
limited disease activity. In these cases, diagnosis is based on rapid
positive response to low-dose prednisone (10-15 mg/day).
• The C-reactive protein level is often
elevated and may parallel the ESR. Studies suggest that high-sensitive
CRP may be a more specific test than the ESR for the diagnosis of PMR.
• The complete blood cell test reveals
mild normocytic, normochromic anemia in 50% of cases. The white blood
cell count may be normal or mildly elevated. Platelet counts are often
increased.
• Liver function tests reveal normal
transaminase enzyme levels. Alkaline phosphatase may be mildly
increased. Serum albumin levels may be slightly decreased.
• The creatine kinase level is normal;
this finding helps differentiate PMR from polymyositis and other
primary myopathic disorders.6
•
Finally,
antinuclear antibodies and rheumatoid factor levels are usually normal,
and serum interleukin-6 levels are elevated and often closely parallel
the inflammatory activity of the disease.6
Radiographic Diagnosis
Radiography of painful joints may rarely show
abnormalities such as osteopenia, joint space narrowing, or erosions.
Magnetic resonance imaging (MRI) is not necessary for diagnosis, but
MRI of the shoulder reveals subacromial and subdeltoid bursitis and
glenohumeral joint synovitis in the vast majority of patients. MRI of
the hands and feet demonstrates inflammation of the tendon sheaths in
many patients.
Ultrasonography is very operator
dependent but may be useful when the diagnosis is uncertain. Bursa
ultrasonography may reveal an effusion within the shoulder bursae. The
ultrasonography findings and those of MRI usually correlate well.7
Temporal Artery Biopsy (TAB)
Why is this test important? Patients
should be monitored for symptoms or signs of arteritis after treatment
initiation, because low-dose corticosteroids such as prednisone do not
prevent progression of PMR to GCA. If clinical signs of vasculitis
develop, TAB should be performed.
TAB may also be warranted in patients
with PMR who are receiving low-dose corticosteroids if the clinical
response is incomplete or if the ESR remains elevated or rises despite
symptom resolution on corticosteroid therapy.7,8
Treatment
The goals of therapy in PMR are to
control painful myalgia, to improve muscle stiffness, and to resolve
constitutional features of the disease. Oral corticosteroids such as
prednisone (see sidebar) are the first line of treatment. Nonsteroidal
anti-inflammatory drugs (NSAIDs) may be helpful as adjuncts to
corticosteroids during tapering, or alone in mild cases.9
PMR is usually a self-limiting disease.
If untreated, patients will have an impaired quality of life. With
early diagnosis and correct therapy, patients have an excellent
prognosis. The average length of disease is 3 years. However,
exacerbations may occur if steroids are tapered too rapidly, and
relapse is common, affecting up to 25% of all treated patients.
Generally, PMR is not associated with
serious complications; however, patients treated with corticosteroids
are at risk for long-term complications of corticosteroid therapy.
Every patient should be considered at risk for GCA.
Corticosteroids are considered the
treatment of choice because they often cause complete or near-complete
symptom resolution and reduction of the ESR to normal. However, they do
not cure the disease. The low-dose corticosteroids used in PMR are
almost certainly ineffective in the prevention of vasculitis
progression.
It has been found that remission of PMR
seemed to be achieved with a 15-mg/d dose of prednisone for most
patients. A slow tapering of the prednisone, less than 1 mg/mo, was
associated with fewer relapses.
Nevertheless, controversy remains
regarding the dose and duration of treatment. The dose depends on the
patient’s weight and the severity of symptoms. The dose should be
increased if symptoms are not well controlled within 1 week, and a
diagnosis of GCA may need to be pursued. In contrast to results with
other rheumatic diseases, alternate-day administration of
corticosteroids in PMR has been largely unsuccessful.9
NSAIDs may provide supplemental pain
relief. They may be used alone in the treatment of patients with mild
symptoms; however, most patients require corticosteroids for total
control of symptoms. NSAIDs may be helpful in later stages of
corticosteroid dosage tapering and generally have no effect on the ESR.
Methotrexate, azathioprine, and other
immunosuppressive therapies are seldom used in PMR treatment.
Occasionally, they may be considered in patients with corticosteroid
intolerance or as corticosteroid-sparing agents.
In fact, symptomatic palliation of pain
with analgesic therapy alone may be preferable in patients with
intolerable adverse effects from corticosteroids (e.g., uncontrolled
diabetes mellitus, severe symptomatic osteoporosis, psychosis).8
Long-Term Monitoring
PMR requires a primary care physician,
rheumatologist, ophthalmologist, pathologist, and surgeon on an
as-needed basis. Both the primary care physician and the rheumatologist
play an important role in diagnosis, treatment, and follow-up care.
Consultation with an ophthalmologist is important if concomitant GCA
causes decreased vision. Consultation with a surgeon for performance of
TAB is essential if the presence of GCA is in doubt.
PMR is typically treated in an
outpatient setting. Patients receiving steroids should have monthly
follow-up, with regular monitoring of the ESR. An isolated increase of
the ESR without symptoms during the course of treatment is not a valid
reason to increase the corticosteroid dose; however, a temporary delay
in dose reduction may be necessary. After steroid tapering, follow-ups
can be performed quarterly.
To prevent osteopenia or
osteoporosis during the treatment, supplementation with calcium
(1,000-1,200 mg/day) and vitamin D (up to 1,000 IU/day) should be
initiated in all patients with PMR who are starting corticosteroid
therapy.11
Because relapses are more likely to
occur during the initial 18 months of therapy and within 1 year of
corticosteroid withdrawal, all patients should be monitored for symptom
recurrence throughout corticosteroid tapering and until 12 months after
cessation of therapy.
Approximately 50% to 75% of patients can
discontinue corticosteroid therapy after 2 years of treatment, and
patients with PMR should be monitored regularly and carefully for
symptoms and signs suggestive of GCA development.11
REFERENCES
1. Salvarani C, Cantini F, Hunder GG. Polymyalgia rheumatica and giant-cell arteritis. Lancet. 2008;372(9634):234-245.
2. Michet CJ, Matteson EL. Polymyalgia rheumatica. BMJ. 2008;336(7647):765-769.
3. Dasgupta B, Salvarani C, Schirmer M, et al. Developing
classification criteria for polymyalgia rheumatica: comparison of views
from an expert panel and wider survey. J Rheumatol. 2008;35(2):270-277.
4. Dasgupta B, Hassan N. Giant cell arteritis: recent advances and guidelines for management. Clin Exp Rheumatol. 2007;25(1 suppl 44):S62-S65.
5. Dasgupta B, Matteson EL, Maradit-Kremers H. Management guidelines and outcome measures in polymyalgia rheumatica (PMR). Clin Exp Rheumatol. 2007;25(6 suppl 47):130-136.
6. MayoClinic. May 17, 2008.
http://web.archive.org/web/20080623203621/http://www.mayoclinic.com/health/polymyalgia-rheumatica/DS00441/DSECTION=tests-and-diagnosis.
Accessed January 19, 2012.
7. Hellmann DB, Imboden JB Jr. Polymyalgia rheumatica and
giant cell arteritis section of musculoskeletal and immunologic
disorders. In: SJ McPhee, MA Papadakis, eds. Current Medical Diagnosis and Treatment. 49th ed. New York, NY: McGraw-Hill; 2010:766-767.
8. Both M, Aries PM, Muller-Hulsbeck S, et al. Balloon
angioplasty of arteries of the upper extremities in patients with
extracranial giant-cell arteritis. Ann Rheum Dis. 2006;65(9):1124-1130.
9. Hellmann DB. Giant cell arteritis, polymyalgia
rheumatica, and Takayasu’s arteritis. In: GS Firestein GS, Budd RC,
Harris ED Jr, et al, eds. Kelley’s Textbook of Rheumatology. Vol 2. 8th ed. Philadelphia, PA: Saunders Elsevier; 2008:1409-1428.
10. MayoClinic. December 4, 2010. www.mayoclinic.com/health/polymyalgia-rheumatica/DS00441/DSECTION=risk-factors. Accessed
January 19, 2012.
11. MayoClinic. May 17, 2008.
http://web.archive.org/web/20080623203610/http://www.mayoclinic.com/health/polymyalgia-rheumatica/DS00441/DSECTION=lifestyle-and-home-remedies.
Accessed January 19, 2012.
To comment on this article, contact rdavidson@uspharmacist.com.
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